file download method in visual studio 2017

Question

That download method is not working for my project, please I need help, since I am working on .xaml and .xaml.cs

private void OnDescargarDocumento() {

        foreach (var item2 in ListadoInfDoc)
        {
            Num_CodDocumentos = item2.Num_CodDocumentos;
            Bin_Imagen = item2.Bin_Imagen;
            Tx_ImagenMIME = item2.Tx_ImagenMIME;
            Tx_NombreArchivo = item2.Tx_NombreArchivo;
        }

        SaveFileDialog saveFileDialog = new SaveFileDialog();
        saveFileDialog.FileName = Tx_NombreArchivo;
        saveFileDialog.Filter = "All files (*.*)|*.*";

        if (saveFileDialog.ShowDialog() == DialogResult.OK)
        {
            
            File.WriteAllBytes(saveFileDialog.FileName, Bin_Imagen);
        }
    }